1. Field of the Invention
This invention relates in general to load bearing pendant systems and specifically to pendants used in conjunction with overhead conveyor systems for displacing an article or work piece in a manufacturing or processing plant. More specifically, this invention relates to the movement of articles successively through a series of positions in which different operations are performed thereon, such as cleaning, spray painting, hand painting, baking, or the like while the work piece is rotating or during the times between such rotations.
2. Prior Art
Specifically, during spraying and coating operations, it has often been found necessary to rotate a work piece continuously while applying spray to it as it is moved by an overhead conveyor. At other times, the spraying or coating operation has required that the work piece remain at a particular angular orientation for a fixed time interval while it travels between two points on a conveyor line. Subsequent to this time interval the object is rotated to a second angular orientation while traveling between other points on the line.
Due to the fact that it is sometimes necessary to continuously rotate the work piece, and at other times to index the rotation in discrete increments, the industry has over the years developed two different types of pendant systems for use with overhead conveyors. The first such type of pendant is specifically designed for continuously rotating a work piece and is usually rotatably mounted to the conveyor. It is customary to provide a fixed stationary length of chain parallel to the conveyor situated between the conveyor and the work piece. This chain engages a sprocket on this type of pendant system and as the conveyor carries the pendant and work piece past the stationary chain, the pendant is continuously rotated by the inter-action of its sprocket teeth with the stationary chain.
For manufacturing or processing operations requiring indexed rotation, a second type of pendant system has been developed. These indexing type pendants do not have sprockets to continuously engage a stationary chain. Rather, they have been designed to remain in fixed position at various angular orientations. A cam is hung in the vacinity of the pendant at each indexing point and as the pendant passes the indexing point and engages the cam, it is forced to rotate to its next angular orientation.
Particular spraying or processing operations require a great many hangers, and when operations are carried out that require both continuous rotation and index rotation at various times in the operation, it becomes necessary to stock a full complement of both types of pendant systems. Such a requirement leads to increased capital costs. In addition, when changing from one type of pendant to another, considerable time and money is lost during the required down time.